Giraffe

From New World Encyclopedia
Revision as of 19:41, 26 July 2007 by Rick Swarts (talk | contribs)
Giraffe
Giraffe standing.jpg
Conservation status
Status iucn2.3 CD.svg
Conservation Dependent
[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Giraffidae
Genus: Giraffa
Species: camelopardalis
Binomial name
Giraffa camelopardalis
Linnaeus, 1758
Range map
Range map

The giraffe (Giraffa camelopardalis) is an African even-toed ungulate mammal that has a very long neck and legs and is the tallest of all land-living animal species. Males can be 4.8 to 5.5 meters (16 to 18 feet) tall and weigh up to 1,360 kilograms (3,000 pounds). Females are generally slightly shorter (up to 4.3 meters or 14 feet) and weigh less than the males do (up to 680 kilograms or 1,500 pounds) (ZSSD 2007).

Giraffe's have the longest tail of any land mammal (up to 2.4 meters or 8 feet) and a spotted pattern reminiscent of the leopard (and thus the origin of the species name) (ZSSD 2007).

As an even-toed ungulate (order Artiodactyla), the giraffe is related to deer and cattle, but is placed in a separate family, the Giraffidae, consisting only of the giraffe and its closest relative, the okapi. It is native to most of Sub-Saharian Africa with its range extending from Chad to South Africa.

Description

Giraffes use their long, prehensile tongues to extend their reach. Specimen at the National Museum of Natural History, Washington, DC.
Ossicones of a Reticulated giraffe.

Giraffes are the tallest land animals, reaching 5.5 meters (18 feet). The legs and neck are very long, each about 1.8 meters (6 feet) in length. While the basic body pattern is the back sloping down to the hindquarters, with the back legs looking shorter than the front legs, the back and front legs actually are about the same length (ZSSD 2007). Like humans, there are seven neck vertebrae in giraffes, but each vertebrate is considerably larger: each one can be over 25 centimeters (10 inches) long (ZSSD 2007).

Giraffes have spots covering their entire bodies, except their underbellies, with each giraffe having a unique pattern of spots.

Giraffe's have long (46 centimeter or 18 inch), prehensile, blue-black tongues that they can use to manuver around the long thorns of the acacia trees on which they feed on the leaves. They also have thick, sticky saliva that coats any thorns they might swallow (ZSSD 2007). It is thought that the dark color of their tongues protects them from getting sunburned while reaching for leaves on trees (ZSSD 2007). Giraffe's also have large eyes.

Both sexes have horns, although the horns of a female are smaller. The prominent horns are formed from ossified cartilage and are called ossicones. The appearance of horns is a reliable method of identifying the sex of giraffes, with the females displaying tufts of hair on the top of the horns, whereas males' horns tend to be bald on top—an effect of necking in combat with other males. Males sometimes develop calcium deposits which form bumps on their skull as they age, which can give the appearance of up to three further horns (ZSSD 2007).

Skeleton

Modifications to the giraffe's structure have evolved, particularly to the circulatory system. A giraffe's heart, which can weigh up to 10 kg (24 lb) and measure about 2 feet long, has to generate around double the normal blood pressure for an average large mammal in order to maintain blood flow to the brain against gravity. In the upper neck, a complex pressure-regulation system called the rete mirabile prevents excess blood flow to the brain when the giraffe lowers its head to drink. Conversely, the blood vessels in the lower legs are under great pressure (because of the weight of fluid pressing down on them). In other animals such pressure would force the blood out through the capillary walls; giraffes, however, have a very tight sheath of thick skin over their lower limbs which maintains high extravascular pressure in exactly the same way as a pilot's g-suit.[citation needed]

A giraffe's heart is 2 feet (0.6 meters) long and weighs about 25 pounds (11 kilograms), and its lungs can hold 12 gallons (55 liters) of air!

In Artiodactyla, even-toed ungulates, the axis of the leg passes between the third and fourth toes. The weight of most even-toed ungulates is born evenly on the third and fourth toe of each foot with the other toes being absent, or vestigial in the case of most deer. Hippopotamuses and pigs have four functional toes on each foot (Nowak 1983).

Except for hippopotamuses, peccaries, and pigs, all even-toed ungulates digest their food by the process of rumination. Their stomachs are divided into chambers, three for camels and mouse deer and four for the other families (Nowak 1983). After food is swallowed, it is kept in the first chamber for a while where it is partly digested with the help of microorganisms, bacteria, and protists. In this symbiotic relationship, the microorganisms break down the cellulose in the plant material into carbohydrates, which the ungulate can digest. Both sides receive some benefit from this relationship. The microorganisms get food and a place to live and the ungulate gets help with its digestion. The partly digested food is then sent back up to the mouth where it is chewed again and sent on to the other parts of the stomach to be completely digested. The microorganisms themselves are also digested, providing proteins and other nutrients, but not before the community of microorganisms has had a chance to reproduce and give rise to a new generation so the relationship can continue (Lott 2003).

Taxonomy and naming

spotted pattern similar to that of a leopard. For a long time people called the giraffe a “camel-leopard,” because they believed that it was a combination of a camel and a leopard. That's where the giraffe's species name comes from! (ZSSD 2007)

The species name camelopardalis (camelopard) is derived from its early Roman name, where it was described as having characteristics of both a camel and a leopard.[2] The English word camelopard first appeared in the 14th century and survived in common usage well into the 19th century. A number of European languages retain it. The Arabic word الزرافة ziraafa or zurapha, meaning "assemblage" (of animals), or just "tall," was used in English from the sixteenth century on, often in the Italianate form giraffa.


Social structure, reproduction and sexuality

Two males necking.
File:MalindiGiraffe.jpg
Chinese painting of a giraffe brought by Admiral Zheng He and placed in a Ming Dynasty zoo (AD 1414)

Female giraffes associate in groups of a dozen or so members, occasionally including a few younger males. Males tend to live in "bachelor" herds, with older males often leading solitary lives. Reproduction is polygamous, with a few older males impregnating all the fertile females in a herd. Male giraffes determine female fertility by tasting the female's urine in order to detect estrus, in a multi-step process known as the flehmen response.

Giraffe gestation lasts between 14 and 15 months, after which a single calf is born. The mother gives birth standing up and the embryonic sack usually bursts when the baby falls to the ground. Newborn giraffes are about 1.8 metres tall. Within a few hours of being born, calves can run around and are indistinguishable from a week-old calf; however, for the first two weeks, they spend most of their time lying down, guarded by the mother. While adult giraffes are too large to be attacked by most predators, the young can fall prey to lions, leopards, hyenas, and African Wild Dogs. It has been speculated that their characteristic spotted pattern provides a certain degree of camouflage. Only 25 to 50% of giraffe calves reach adulthood; the life expectancy is between 20 and 25 years in the wild and 28 years in captivity.(Encyclopedia of Animals).

The males often engage in necking, which has been described as having various functions. One of these is combat. These battles can be fatal, but are more often less severe. The longer a neck is, and the heavier the head at the end of the neck, the greater force a giraffe will be able to deliver in a blow. It has also been observed that males that are successful in necking have greater access to estrous females, so that the length of the neck may be a product of sexual selection.[3]

After a necking duel, a giraffe can land a powerful blow with his head occasionally knocking a male opponent to the ground. These fights rarely last more than a few minutes or end in physical harm.

Other behaviour

Giraffe, Melbourne Zoo

The giraffe browses on the twigs of trees, preferring trees of the genus Mimosa; but it appears that it can live without inconvenience on other vegetable food. A giraffe can eat 63 kg (140 lb) of leaves and twigs daily. As ruminants, they first chew their food, swallow for processing and then visibly regurgitate the semi-digested cud up their necks and back into the mouth, in order to chew again. This process is usually repeated several times for each mouthful.

The pace of the giraffe is an amble, though when pursued it can run extremely fast. It can not sustain a lengthened chase. Its leg length compels an unusual gait with the left legs moving together followed by right (similar to pacing) at low speed, and the back legs crossing outside the front at high speed.

The giraffe defends itself against threats by kicking with great force. A single well-placed kick of an adult giraffe can shatter a lion's skull or break its spine.

The giraffe has one of the shortest sleep requirements of any mammal, which is between 10 minutes and two hours in a 24-hour period, averaging 1.9 hours per day.[4] This has led to the myth that giraffes cannot lie down and that if they do so, they will die.

A giraffe will clean off any bugs that appear on its face with its extremely long tongue (about 18 in/45 cm). The tongue is tough on account of the giraffe's diet, which includes thorns from the tree it is making a meal. In Southern Africa, giraffes are partial to all acacias — especially Acacia erioloba — and possess a specially-adapted tongue and lips that appear to be immune to the vicious thorns.

Giraffes are thought to be mute; however, although generally quiet, they have been heard to grunt, snort and bleat. Recent research has shown evidence that the animal communicates at an infrasound level.[5]

Giraffes are one of the very few animals that cannot swim at all.

The instinct of some other African animals is to stay close to the giraffe, for the giraffe's high vantage point can see predators from far away.[6]

Classification

There are nine generally accepted subspecies, differentiated by color and pattern variations and range:

  • Reticulated or Somali Giraffe (G.c. reticulata) — large, polygonal liver-colored spots outlined by a network of bright white lines. The blocks may sometimes appear deep red and may also cover the legs. Range: northeastern Kenya, Ethiopia, Somalia.
  • Angolan or Smoky Giraffe (G.c. angolensis) — large spots and some notches around the edges, extending down the entire lower leg. Range: Angola, Zambia.
  • Kordofan Giraffe (G.c. antiquorum) — smaller, more irregular spots that cover the inner legs. Range: western and southwestern Sudan.
  • Masai or Kilimanjaro Giraffe (G.c. tippelskirchi) — jagged-edged, vine-leaf shaped spots of dark chocolate on a yellowish background. Range: central and southern Kenya, Tanzania.
  • Nubian Giraffe (G.c. camelopardalis) — large, four-sided spots of chestnut brown on an off-white background and no spots on inner sides of the legs or below the hocks. Range: eastern Sudan, northeast Congo.
  • Rothschild Giraffe or Baringo Giraffe or Ugandan Giraffe (G.c. rothschildi) — deep brown, blotched or rectangular spots with poorly defined cream lines. Hocks may be spotted. Range: Uganda, north-central Kenya.
  • South African Giraffe (G.c. giraffa) — rounded or blotched spots, some with star-like extensions on a light tan background, running down to the hooves. Range: South Africa, Namibia, Botswana, Zimbabwe, Mozambique.
  • Thornicroft or Rhodesian Giraffe (G.c. thornicrofti) — star-shaped or leafy spots extend to the lower leg. Range: eastern Zambia.
  • West African or Nigerian Giraffe (G.c. peralta) — numerous pale, yellowish red spots. Range: Niger, Cameroon.

Some scientists regard Kordofan and West African Giraffes as a single subspecies; similarly with Nubian and Rothschild's Giraffes, and with Angolan and South African Giraffes. Further, some scientists regard all populations except the Masai Giraffes as a single subspecies. By contrast, scientists have proposed four other subspecies — Cape Giraffe (G.c. capensis), Lado Giraffe (G.c. cottoni), Congo Giraffe (G.c. congoensis), and Transvaal Giraffe (G.c. wardi) — but none of these is widely accepted.


Gallery

References
ISBN links support NWE through referral fees

[7]

  • Grzimek, B., D. G. Kleiman, V. Geist, and M. C. McDade. 2004. Grzimek's Animal Life Encyclopedia. Detroit: Thomson-Gale. ISBN 0787657883.

External links

Commons
Wikimedia Commons has media related to::
Wikispecies-logo.svg
Wikispecies has information related to:
Giraffe

Credits

New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:

The history of this article since it was imported to New World Encyclopedia:

Note: Some restrictions may apply to use of individual images which are separately licensed.

  1. Antelope Specialist Group 1996. [1]. 2006 IUCN Red List of Threatened Species., World Conservation Union. Retrieved on 05 May 2006.
  2. http://www.eaudrey.com/myth/camelopard.htm
  3. Robert E. Simmons and Lue Scheepers: Winning by a neck: Sexual selection in the evolution of giraffe. The American Naturalist, 148 (1996): pp. 771-786.
  4. http://www.bbc.co.uk/science/humanbody/sleep/articles/whatissleep.shtml
  5. http://www.animalvoice.com/Giraffe.htm
  6. http://www.sa-venues.com/wildlife/wildlife_giraffe.htm
  7. San Diego Zoo giraffe fact sheetZoological Society of San Diego Retrieved 14 August 2006.